Fort Worth daily gazette. (Fort Worth, Tex.) 1882-1891, 1887-05-01

has seen the Niobrara shales of the west.
Where the protecting limestone has been
washed away, the shales weather into a
gently undRlatlng prairie, with a predis
position to that character locally known
as "hog wallow." This is the second
character of prairie, a prairie resulting
from weathering OF shales;it extends as
narrow strip along the western edge of
THE ROTTEN LIMESTONE REGION,
but fades out before reaching the center
OF the state.
Continuing westward the next topo-
graphic feature is the belt offorest region
known as the CLOVER Cross Timbers"
Geologically the area occupied by these
timbers consists of series OF coarse,
frisble, arenaceous sandstones, elterna-
ting with cIays, whose position is beneath
the shales and hmestones; and, like them,
Its western projecting margin is con-
stantly wearing away. The unique fauna,
now being studied by DR.. G. A. White,
and the presence of Iignites, indicate that
the sediments are those of shallow waters;
they resemble the basal groups of the els
Mississippi region, and, DR.. White be-
lieves, the Dakota sandstOnes OF Kansas.
Elsewhere than IN Texas this group
would be considered the base of the creta
ceous: but such is not the case here, for
it clearly rests upon four hundred feet of
a second, and lower series of limestone
strata and one that was greatly eroded
before these sands were deposited. This
is the "Texas" group of the American
cretaceous-the probability of the exis-
tence of which l pointed out in previous
paper, and which is no demonstrated to
be lower than any of the hitherto describ-
ed marine cretaceous of this country.
This limestone formation underlies the
third character of prairie, which extends
parallel with and between the two Cross
Timbers The strata are bands of vary
ing thickness of yellow-white limestOnes
of peculiar structure, alternating with
calcareous cIays and marls OF the same
color. The prairie extends from
-FOUR MILES EAST OF FORT WORTH
to seven miles west of Weatherford. In
crossing it the strata from top to bottom
are successfully passed. Its surface is
barren and rocky, excepting in rainy sea-
sons, and slopes at a much greater angle
to the southeast than the others we have
described. This was known to old
travellers as the "Grand Prairie," term
which is worthy of preservation. One OF
the strata of limestone presents much
greater resistance to the constantly at
lacking forces of erosion than the others.
AS q result of this fact it forms q table
land for many miles, and is the highest
portion of the prairie. The huge ammon-
ties which are Characteristic of this hOri-
ZOn, project everywhere through the thin
soil. This is the third character OF prai-
RE, prairie resultiog from resistance.
The western edge of this prairie projects
as an esCarpment above the next tCpO-
graphic feature that we here describe.
The ragged edge is we'll marked, and from
it we look down upon the Upper Cross
TImbers to the westward. Sometimes
we can see the fat topped buttes, left by
the constantly reCeding line, IS remnants
of the formations former extent. These
buttes sometimes appear like islands ris-
ing from the depression occupied by the
Cross Timbers, but usually they are
situated on the edge of the adjacent
prairie region. They are generally capped
by the same peculiar stratum of lime
stone, resting upon lOOser strata that
quickly wash away when the cap sue
Cumbs. Sometimes they appear as mere
hillOcks, representing remnants of the
buttes from which this protecting stratum
has been erOded. These buttes are the
most prominent features of this area of
greatest denudation, and are distributed
over it usually upon and around the edge
of the carbOniferous exposures. From
the top of these buttes and
THE EDGE OF GRAND PRAIRIE,
the Cross Timbers look like the waters of
a long and narrow lake viewed from an
adjacent highland, and in some cases, the
opposite shore, as in COmanChe county,
may be recognized. But the resemblance
to a lake is only superficial. 1t is q case
of pseudOmorphism, if may be allowed
to use that expression, wherein the forces
of sub-aerlal erosion have initiated those
of wind and wave. The essential features
of shore topography and lacustrine sedi-
mentation are absent. The marks of ero-
sion are plainly evident.
On descending the escarpment at the
western edge of the Grand Prairie, we
reach the sandy soil of the Upper Cross
Timbers. A geologic section will show
that the surface soil is detritus OF The
underlying strata, which dip to the east,
under the adjacent limestone prairie.
This series of sandy strata varies in
structure SIS we descend them. The
upper strata abound in DinOsaurian
bones and teeth, the lower in Lepidoden.
drons and Calamites. They mark the con-
tact of the basal mesOZoiC and the carbon
ferrous.
The sands of the eastern half of the
Upper Cross Timbers are purely siliceOus,
fine-grained, and utterly free from any
cementing matrix. They are so triable
that they quickly lose all appearance of
original qualification on exposure, and
were it not for railroad-cuts and wellbor-
ings through the everything cretaceOus
limestone, their true straitigraphic posi-
ton would still remain obscure. The
pure white sands of this series can be
traced alOug the eastern border of the
Cross Timbers for over hundred miles.
These sands constitute the receiving
reservoir for
THE ARTISAN WELLS OF FORT WORTH
and Dallas, their strata dipping at such
an angle under the Grand Prairie, that
they are reached at depth Of $50 feet
beneath the first named place, and about
$50 at the latter.) The detrltus of this
stratum has been distributed over most
of the Upper Cross Timbers, so as to OBJ
scure the exact contact of the cretaceous
if the DinOsaurian sands be cretaceous
and the carbonifer0us. But close in
speCtion will reveal the underlying car
boniferous sands and conglomerates IN
stu, accompanied by characteristic fos-
sis.
West of the Upper Cross Timbers the
Texas and Pacific road traVerses the car
boniferous for q hundred miles. In
places, patches of the cretaceous are pre-
served upon it; in others, the carboni-
ferrous itself is greatly eroded. At
point between 9th and the 99th meri-
dians the greatest denudation has taken
place. West Of this the succession of the
strata is again an ascending one. The
red beds of the Jura Trias are iatercalated
between the cretaceous and the corboni-
ferrous on the western side of the latter
formation. The arenaCeous beds are
again eSnnsed in nlaces. esneciallY at the